Currently, refrigerators existing in the markets mainly include two kinds that are direct cooling refrigerators and air-cooled refrigerators according to the refrigerating mode. With the user's growing demands for use and continuous improvements of manufacturing technologies in the refrigerator industry, the air-cooled refrigerator has been well received by the consumers because of its good temperature control ability, no frost in the refrigerator, better preservative effect and the like advantages, and gradually becomes the mainstream product in the market. The refrigerating method thereof is generally that due to the pressure caused by a fan, cold air is sucked out from an evaporator of a freezer compartment and then distributed to each compartment by an air duct device.
The existing air-cooled refrigerators mostly adopts an electric switching valve to switch the refrigerant and can't provide the cold air to each compartment in the air-cooled refrigerator simultaneously, the cooling rate is low. The cold air having passed through the evaporator needs to be discharged by using two or more fans, and the cold air needs to be transferred to each compartment of the air-cooled refrigerator through different air inlet ducts, the overall structure is complicated, the energy consumption of a plurality of fans is great, and the cold air needs to be input into each compartment by an independent air inlet duct, which occupies the limited space of the back of the air-cooled refrigerator, moreover the plurality of independent air inlet ducts will increase the production cost. In addition in the air-cooled refrigerator, an air return duct of a refrigeration compartment and an air return duct of a temperature changeable compartment are mostly in communication, return air in the refrigeration compartment has a large temperature difference and a large humidity difference from return air in the temperature changeable compartment, they are gathered on the evaporator together, easily leading to frost formation on the evaporator and an air duct mouth. If the frost is formed, greater energy consumption will be needed for defrosting, hence the energy consumption of the air-cooled refrigerator is increased. Furthermore, an air inlet control device is not disposed in the refrigeration compartment and the temperature changeable compartment generally, so a volume of air entering the refrigeration compartment and the temperature changeable compartment cannot be controlled accurately, which will reduce the accuracy of temperature control of the air-cooled refrigerator or increase the energy consumption of the air-cooled refrigerator.